There has been known a solar power generation system that uses a solar cell for photoelectrical conversion of the sunlight. Although the solar cell generates DC power, load devices in general are normally driven with AC power. Therefore, the solar power generation system converts the DC power into the AC power by using an inverter.
Incidentally, based on an amount of solar radiation on the solar cell and temperature, an operation point, i.e., an operation current and/or an operation voltage for generating maximum power vary. In order to make effective use of the solar cell, accordingly, it is required that the solar cell be powered by the operation current and/or the operation voltage that maximize the power generation of the solar cell of the situation.
For determination on the operation voltage and the like that maximize the power generation, a hill climbing method that detects the power generation of the solar cell while periodically changing the operation voltage of the solar cell and tracks a maximum output point has been known as one of maximum power point tracking (MPPT: Maximum Power Point Tracking) controls (see Patent Document 1).